It is a GM event...I wonder why they are making two special appearances and telling us the code in-game instead of posting it on the POTCO main site like the other codes.
I mean, they HAVE to have known about all the different ways that word would spread almost instantly. A guildie said the code like 5 minutes before a GM was scheduled to arrive, I announced it to the people waiting with me in local, they told their guilds, and so on.